Irish President Michael D Higgins is to face more questions over a culture of "extravagance" in Aras an Uachtarain after shifting the blame for flying to Belfast from the PSNI to his own officials.

Already Mr Higgins has changed his story as to why he flew to Belfast last May to give a lecture at Queen's University.

Last week he indicated that the decision was made on foot of consultations with the PSNI who were not in a position to provide security for him to travel by road.

However, he has now said the Government jet, which costs €4,000 an hour to operate, was called upon because of advice from his own officials.

"I have visited Northern Ireland many times in the last seven years and I take the advice from my office and my office judges these trips in terms of- the considerations they take into account are logistics and security," he said.

The President was asked on three occasions to clarify on what basis the jet was deemed necessary, but refused.

"No, I've answered the question. I really don't ... quite frankly to say, now and in the future, I am very happy to accept the advice of my office, they balance the issue, their considerations are ones of logistic and security," Mr Higgins said.

The President added that he is "very happy with the official PSNI statement" which said they could not comment on the security arrangements of individuals.

However, PSNI sources separately said there was anger at the suggestion that the force did not have sufficient resources to provide a police escort.

Another source said: "It would be inconceivable that the President of Ireland would not have been afforded security if it had been requested."

Questions over the use of the jet are likely to feature in the final televised debate tonight.

Businessman Gavin Duffy said extravagance "seems to be embedded in the culture of Aras an Uachtarain".

He said controversies over the use of the jet and an unaudited €317,000 fund for the Aras "are starting to register with people".

But the Dragons' Den investor admitted it would take something "seismic" to unseat Mr Higgins.

Sinn Fein's candidate Liadh Ni Riada has asked Mr Higgins to explain the "huge public expense to fly within the island of Ireland, to places like Belfast and Kerry".

However, Joan Freeman appealed for candidates to move back to debating their vision for the presidency.